Took apart my shower faucet cartridge assembly and found that the seats appear to be worn, causing some dripping. Applying some silicon sealant, cleaning, and reassembling has fixed the problem for now, but I'd like to replace the seats. They look much like RP1806 but it is hard to tell from a picture. I measured the seats and mine are about .44" outside diameter, .327" inside diameter , .285" tall, and has a flat face (not curved like some). Can you tell me what part I need?